During the Citizen Army's inception in 1913, he was a member of the group's initial provisional council alongside Captain Jack White, James Larkin, P. T. Daly and Constance Markievicz,[1] and would go on to take up a permanent position on its executive committee.

[7] Six years after returning to Ireland, Poole was elected to the founding provisional committee of the Irish Citizen Army alongside Jack White, Constance Markievicz and Jim Larkin.

Primarily Larkin, Seán O’Casey, Markievicz and other members of the ITGWU drew up a new constitution, calling for an ‘army council’ and included explicitly nationalist aims.

When Mallin ordered the evacuation of the Green on Tuesday 25 April, Poole organised the fall back to the Royal College of Surgeons which had been secured by Constance Markievicz prior.

[14] After Padraig Pearse's surrender order was accepted by the British side, Poole was tried and sent to Stafford Jail detention barracks in England before being transferred to Frongoch internment camp in Wales with the majority of the remaining soldiers.

On the Dublin docks in 1918, Poole led a battalion of ICA men and secured a huge windfall of ammunition from an American transport vessel, the Defiance, which had served as a cargo ship in the United States Navy during the late stages of the Great War.

In spite of all the difficulties the booty was too valuable to lose, and relays of Citizen Army men were down on the quays for eight hours a day, taking the revolvers and ammunition from those who succeeded in getting the necessary shore permits.